Image grid - wrap items within panel

I'm trying to put 100 images (50x50pixels) in a panel that is 500x500pixels. I want 10 images per line, right next to one another, filling up the entire panel. I've been stuck for 2 days on this, and would really appreciate help. The code as follows:

note: i've also tried with a 10x10 array, listing each row as a different item with vbox, but it didn't work. thank you in advance for any help!